Urodynamic tests are diagnostic procedures, the purpose of which is to assess the physiologic properties of the lower urinary tract, i.e. the bladder and urethra.
The urinary bladder and the urethra work together as a unit to serve the double purpose of collecting and conveying urine. The bladder is composed mostly of small muscles which are to a large degree under voluntary control. Muscle bundles run in different directions and from layer to layer.
The adaptation of the bladder to the changing urine volume is mainly due to the viscal-elastic property of the organ. The bladder wall, in a healthy individual, is able to expand without any significant increase in tension as the bladder fills with urine. One of the major urodynamic tests involves filling the bladder with a saline solution, and simultaneously measuring the intravesical pressure. The plot of pressure against volume of contents during this filling is called a cystometrogram, and the early portion of this graphical representation of pressure against volume is substantially flat in a healthy individual. When the individual is instructed to void, or when the urge to void arises automatically, the pressure inside the bladder increases.
Another standard urodynamic test is called the urethral pressure profile (UPP). This test is typically carried out by inserting a catheter having a side opening and a lumen communicating with that opening. A dilute saline solution is pumped into the lumen and out through the side opening at a fixed rate, while the catheter is steadily withdrawn from the urethra at a substantially constant speed. A plot of the back pressure in the line between the pump and the side opening, against the physical distance of the opening along the urethra, yields the UPP. Typically, as the opening passes a location of constriction, whether normal or abnormal, the back pressure rises, and appears as a spike or hump in the graphical representation of pressure against distance.
Another factor related to the test just mentioned is the functional profile length, which is basically the length of the urethra over which the pressure profile is taken.
One of the important parameters derived from the urethral pressure profile test (UPP) is what is called the maximum urethral closure pressure, which is the difference between the maximum pressure derived by the UPP test and the intravesical pressure of the bladder.
Prior patents of interest to this subject matter are as follows:
U.S. Pat. No. 4,136,681, issued Jan. 30, 1979, to Edward H. Hon PA1 U.S. Pat. No. 168,703, issued Jan. 30, 1979, to Kenneth Kenigsberg PA1 U.S. Pat. No. 4,191,196, issued Mar. 4, 1980, to Bradley et al PA1 U.S. Pat. No. 4,217,911, issued May 5, 1981, to Terry N. Layton PA1 U.S. Pat. No. 4,252,131, issued Feb. 24, 1981, to Hon et al PA1 U.S. Pat. No. 4,006,735, issued Feb. 8, 1977, to Hittman et al PA1 U.S. Pat. No. 4,023,562, issued May 17, 1977, to Hynecek et al PA1 U.S. Pat. No. 3,480,003, issued Nov. 25, 1969, to N. A. Crites PA1 U.S. Pat. No. 4,265,243, issued May 5, 1981, to Glenn N. Taylor PA1 U.S. Pat. No. 4,301,811, issued Nov. 24, 1981, to Terry N. Layton PA1 U.S. Pat. No. 3,437,088, issued Apr. 8, 1969, to L. J. Bielinski PA1 U.S. Pat. No. 4,214,593, issued July 29, 1980, to Imbruce et al